The light is emitted by the laser diode and enters a diffraction grating. 激光束从激光二极管中发出，射入衍射光栅。
When the laser beam goes through the diffraction grating, it is split up into a central bright beam plus a number of side beams. 当激光束射入衍射光栅后，被分成一个中间的明亮光束和一些处于旁边的光束。
